A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous tracks, though specialized models riding on large off-road tires are also produced. Its most popular accessory is a ripper, a large hook-like device mounted singly or in multiples in the rear to loosen dense materials.
Bulldozers are used heavily in large and small scale construction, road building, minings and quarrying, on farms, in heavy industry factories, and in military applications in both peace and wartime.
The word "bulldozer" refers only to a motorized unit fitted with a blade designed for pushing. The word is sometimes used inaccurately for other heavy equipment such as a front-end loader designed for carrying rather than pushing material. The term originally referred only to the blade attachment but is now commonly applied to any crawler tractor with a front mounted blade.
Description
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A Liebherr bulldozer with a straight bladeThe same bulldozer's multishank ripperTypically, bulldozers are large and powerful tracked heavy equipment. The tracks give them excellent traction and mobility through very rough terrain. Wide tracks also help distribute the vehicle's weight over a large area (decreasing ground pressure), thus preventing it from sinking in sandy or muddy ground. Extra-wide tracks are known as swamp tracks or low ground pressure (lgp) tracks. Bulldozers have transmission systems designed to take advantage of the track system and provide excellent tractive force.
These traits allow bulldozers to excel in road building, construction, mining, forestry, land clearing, infrastructure development, and any other projects requiring highly mobile, powerful, and stable earth-moving equipment.
A variant is the all-wheel-drive wheeled bulldozer, which generally has four large rubber-tired wheels, hydraulically operated articulated steering, and a hydraulically actuated blade mounted forward of the articulation joint.
The bulldozer's primary tools are the blade and the ripper:
Blade
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Bulldozer blade Komatsu bulldozer pushing up to 7 m3 with semi-U tilt dozerBulldozer blades come in three types:
Blades can be fitted straight across the frame, or at an angle. All can be lifted, some, with additional hydraulic cylinders, can be tilted to vary the angle up to one side.
Sometimes, a bulldozer is used to push or pull another piece of earth-moving equipment known as a "scraper" to increase productivity. The towed Fresno Scraper, invented in 1883 by James Porteous, was the first design to enable this to be done economically, removing the soil from an area being cut and depositing where needed as fill. Dozer blades with a reinforced center section for pushing are known as "bull blades".
Dozer blades are added to combat engineering vehicles and other military equipment, such as artillery tractors such as the Type 73 or M8 Tractor, to clear battlefield obstacles and prepare firing positions.[1] Dozer blades may be mounted on main battle tanks to clear antitank obstacles or mines, and dig improvised shelters.
Ripper
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Multishank ripper A Caterpillar D10N bulldozer equipped with a single-shank ripperA ripper is a long, claw-like shank that may be mounted singly or in multiples on the rear of a bulldozer to loosen hard and impacted materials. Usually a single shank is preferred for heavy ripping. The ripper is equipped with a replaceable tungsten steel alloy tip, known as a boot.
Ripping can not only loosen soil (such as podzol hardpan) in agricultural and construction applications but break shaly rock or pavement into easily handled small rubble.
A variant of the ripper is the stumpbuster,[2] a single spike protruding horizontally used to split a tree stump.
Variants
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A tracked loader is designed to transport rather than push or rough-grade materialFurther information on the small airborne bulldozer: Clark CA1
Armored bulldozers
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Bulldozers employed for combat-engineering roles are often fitted with armor to protect the driver from firearms and debris, enabling bulldozers to operate in combat zones. The most widely documented use is the Israeli Military militarized Caterpillar D9, for earth moving, clearing terrain obstacles, opening routes, and detonating explosive charges. The IDF used armoured bulldozers extensively during Operation Rainbow where they were used to uproot Gaza Strip smuggling tunnels and destroy residential neighbourhoods, water wells and pipes, and agricultural land[3][4] to expand the military buffer zone along the Philadelphi Route.[4] This use drew criticism against both the use and the suppliers of armoured bulldozers from human-rights organizations such as the EWASH-coalition and Human Rights Watch,[5][6] the latter of whom urged Caterpillar to cease their sale of bulldozers to the IDF. The use of bulldozers was seen as necessary by Israeli authorities to uproot smuggling tunnels, destroy houses used by Palestinian gunmen, and expand the buffer zone.[4][7]
Some forces' engineer doctrines differentiate between a low-mobility armoured dozer (LMAD) and a high-mobility armoured dozer (HMAD). The LMAD is dependent on a flatbed to move it to its employment site, whereas the HMAD has a more robust engine and drive system designed to give it road mobility with a moderate range and speed. HMADs, however, normally lack the full cross-country mobility characteristics of a dozer blade-equipped tank or armoured personnel carrier.
Some bulldozers have been fitted with armor by civilian operators to prevent bystanders or police from interfering with the work performed by the bulldozer, as in the case of strikes or demolition of condemned buildings. This has also been done by civilians with a dispute with the authorities, such as Marvin Heemeyer, who outfitted his Komatsu D355A bulldozer with homemade composite armor to then demolish government buildings.
Remote-controlled dozers
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In recent years, innovations in the construction technology have made remote-controlled bulldozers a reality. Now, heavy machinery can be controlled from up to 1,000 feet away. This contributes to the safety of workers on the jobsite, keeping them at a secure distance from potentially dangerous jobs.
The advancement and the ability to control the heavy machinery from afar provides workers with the sufficient control over the dozers to get the job done. Though these machines are still in their early stages, many construction companies are using them successfully.[citation needed]
History
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The first bulldozers were adapted from Holt farm tractors that were used to plough fields. The versatility of tractors in soft ground for logging and road building contributed to the development of the armored tank in World War I.
In 1923, farmer James Cummings and draftsman J. Earl McLeod made the first designs for the bulldozer. A replica is on display at the city park in Morrowville, Kansas, where the two built the first bulldozer.[8] On December 18, 1923, Cummings and McLeod filed U.S. patent #1,522,378 that was later issued on January 6, 1925, for an "Attachment for Tractors."[9]
By the 1920s, tracked vehicles became common, particularly the Caterpillar 60. Rubber-tired vehicles came into use in the 1940s. To dig canals, raise earthen dams, and do other earth-moving jobs, these tractors were equipped with a large, thick, metal plate in front. (The blade got its curved shape later). In some early models, the driver sat on top in the open without a cabin. The three main types of bulldozer blades are a U-blade for pushing and carrying soil relatively long distances, a straight blade for "knocking down" and spreading piles of soil, and a brush rake for removing brush and roots. These attachments (home-built or built by small equipment manufacturers of attachments for wheeled and crawler tractors and trucks) appeared by 1929.
Widespread acceptance of the bull-grader does not seem to appear before the mid-1930s. The addition of power down-force provided by hydraulic cylinders instead of just the weight of the blade made them the preferred excavation machine for large and small contractors alike by the 1940s, by which time the term "bulldozer" referred to the entire machine and not just the attachment.
Over the years, bulldozers got bigger and more powerful in response to the demand for equipment suited for ever larger earthworks. Firms such as Caterpillar, Komatsu, Clark Equipment Co, Case, Euclid,[10] Allis Chalmers, Liebherr, LiuGong, Terex, Fiat-Allis, John Deere, Massey Ferguson, BEML, XGMA, and International Harvester manufactured large, tracked-type earthmoving machines. R.G. LeTourneau and Caterpillar manufactured large, rubber-tired bulldozers.
Bulldozers grew more sophisticated as time passed. Improvements include drivetrains analogous to (in automobiles) an automatic transmission instead of a manual transmission, such as the early Euclid C-6 and TC-12 or Model C Tournadozer, blade movement controlled by hydraulic cylinders or electric motors instead of early models' cable winch/brake, and automatic grade control. Hydraulic cylinders enabled the application of down force, more precise manipulation of the blade, and automated controls.
In the very snowy winter of 1946–47 in the United Kingdom, in at least one case a remote cut-off village running out of food was supplied by a bulldozer towing a big sled carrying necessary supplies.
A more recent innovation is the outfitting of bulldozers with GPS technology, such as manufactured by Topcon Positioning Systems, Inc., Trimble Inc, or Leica Geosystems, for precise grade control and (potentially) "stakeless" construction. As a response to the many, and often varying claims about these systems, the Kellogg Report[11] published in 2010 a detailed comparison of all the manufacturers' systems, evaluating more than 200 features for dozers alone.
The best-known maker of bulldozers is Caterpillar. Komatsu, Liebherr, Case, Hitachi, Volvo, and John Deere are present-day competitors. Although these machines began as modified farm tractors, they became the mainstay for big civil construction projects, and found their way into use by military construction units worldwide. The best-known model, the Caterpillar D9, was also used to clear mines and demolish enemy structures.
Manufacturers
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Industry statistics based on 2010 production published by Off-Highway Research showed Shantui was the largest producer of bulldozers, making over 10,000 units that year or two in five crawler-type dozers made in the world.[12] The next-largest producer by number of units is Caterpillar Inc., which produced 6,400 units.[12]
Komatsu introduced the D575A in 1981, the D757A-2 in 1991, and the D575A-3 in 2002, which the company touts as the biggest bulldozer in the world.[13]
History of the word
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These appeared as early as 1929, but were known as "bull grader" blades, and the term "bulldozer blade" did not appear to come into widespread use until the mid-1930s. "Bulldozer" now refers to the whole machine, not just the attachment. In contemporary usage, "bulldozer" is sometimes shortened to "dozer", and the verb "bulldozing" to "dozing", thus making a homophone with the pre-existing verb "dozing".
Gallery
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See also
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References
“Neither of these inventors actually built a bulldozer,” said Plant. “They were simply track-laying traction engines,” Plant said. “The scraper blade in the front of the machine is technically the bulldozer, and the machine is referred to as a crawler tractor.”Another contributor to the innovation of the bulldozer is LaPlant-Choate, who produced some of the first bulldozers and motor scrapers. “Some experts believe LaPlant-Choate Mfg. Co of Cedar Rapids, Iowa, first fitted a bulldozer blade to a track laying tractor,” Plant said, “producing the first bulldozer in regular commercial production.” The machine was used in the 1923 construction of the Dixie Highway in Kentucky. LaPlant-Choate took its name from E.W. LePlant, who started the company in 1889 by moving houses and pulling tree stumps, and nephew Roy Choate, joined him in 1911. The company evolved into the business of manufacturing bulldozer and snow plow blades and other equipment, and was sold in 1952 to Allis-Chalmers.Eventually, it was The Caterpillar Tractor Company that came to dominate the bulldozer market. The company was formed in August, 1925, by the merger of Holt’s company and its major competitor, the C. L. Best Gas Tractor Company. The Caterpillar name is attributed to a photographer hired by Holt to take pictures of one of his crawler tractors. The photographer noticed that the rollers looked like a caterpillar when he saw the image upside-down through his camera lens. Holt liked it, and the name stuck. The history of the word “bulldozer” goes back to the 19th century when a bulldozer denoted a horizontal forging press used for shaping and bending metal. Another term, a bull-dose, was a large dose — literally effective for a bull — of any sort of medicine or punishment. Bull-dosing also meant coercion or intimidation. In the late 19th century, bulldozing meant using brute force to push over or through any obstacle, referring to two bulls butting heads in a fight. Today’s term might be a “bully.” During World War 1, Holt crawler tractors were used extensively by both American and British forces as ‘beasts of burden’ hauling heavy artillery and other heavy loads around the front lines where no other vehicles could handle the muddy conditions, Plant noted. It was also during World War 1 that the first tracked armored tanks were developed and were first used in combat by the British Army in September, 1916. In the late 1930s, the tracked vehicles became more common, and they became the go-to machine in the construction industry working on large projects like the building of Hoover Dam and the Golden Gate Bridge. By the 1940s, the term bulldozer referred to the entire machine and not just the attachment. Fleets of bulldozers were used in WWII to construct highways, runways and fortifications. Military bulldozers rumbled through bombed-out villages across Europe, working to clear roads and keep supply lines open, and rolled into camps as they were liberated by Allied forces. They were the first to go ashore on amphibious assaults, including the Normandy landings in 1944. Navy Admiral William Halsey said there were four things that helped win the war in the Pacific – airplanes, tanks, submarines and bulldozers. Over the years, the bulldozer became an American icon. The size and sophistication of the machines grew, with the addition of automatic transmissions, hydraulic cylinders, electric motors, GPS technology and automatic grade control.
“The machine has changed a lot in the last almost 100 years,” Plant noted, “from an attachment on a wheeled farm tractor in 1923 to a fully integrated machine in 2020.”“Many advances have been made over the years in bulldozer blade design and types, in crawler tractor design and in the design of controls for bulldozers. Horsepower has increased by well over 50 times and weights have likewise increased exponentially,” Plant said. “One can only wonder what Cummings and McLeod would think of today’s machines,” he said. What started out as a solution for farmers eventually became a solution for the construction industry. Today, this American icon is just a plain ‘ole “dozer.”
The bulldozer. What was it first? A solution for farmers, or a solution for construction workers? Although it’s unclear who actually invented the first bulldozer, the bulldozer shovel blade has been around long before the first motorized tractors. In fact, the first wooden blade bulldozers were mule-or- horse-powered and used to move dirt as well as smooth rough ground for planting fields…for farmers.Some say the first bulldozer was invented in 1904 by Benjamin Holt who developed an endless chain tread for his steam engine. Around the same time, the Hornsby Company of England also patented their version of a bulldozer which was closer to what is known today as a bulldozer because it was steered by controlling power to each track. Hornsby sold his patents to Holt around 1914. Even though some people refer to these inventions as bulldozers, they were actually crawlers, and not technically bulldozers.Most people, however, give credit for the bulldozer invention to Kansas farmer James Cummings and draftsman J. Earl McLeod who created a scraper blade in 1923. Their patent, approved in 1925, was for a “scraper blade mounted forwardly of the tractor on a pair of pivoting arms which are linked to the sides of the tractor, e.g. bulldozers.”“The tractor to which Cummings and McLeod attached their bulldozer blade was a wheeled farm tractor. From what I can gather, it came about because Cummings had won a contract to backfill a pipeline trench,” said Deas Plant, a specialist in earth-moving and construction plant operations. Plant, who grew up and lives in Brisbane, Australia, has been operating bulldozers for over 50 years.Another contributor to the innovation of the bulldozer is LaPlant-Choate, who produced some of the first bulldozers and motor scrapers. “Some experts believe LaPlant-Choate Mfg. Co of Cedar Rapids, Iowa, first fitted a bulldozer blade to a track laying tractor,” Plant said, “producing the first bulldozer in regular commercial production.” The machine was used in the 1923 construction of the Dixie Highway in Kentucky.LaPlant-Choate took its name from E.W. LePlant, who started the company in 1889 by moving houses and pulling tree stumps, and nephew Roy Choate, joined him in 1911. The company evolved into the business of manufacturing bulldozer and snow plow blades and other equipment, and was sold in 1952 to Allis-Chalmers.Eventually, it was The Caterpillar Tractor Company that came to dominate the bulldozer market. The company was formed in August, 1925, by the merger of Holt’s company and its major competitor, the C. L. Best Gas Tractor Company. The Caterpillar name is attributed to a photographer hired by Holt to take pictures of one of his crawler tractors. The photographer noticed that the rollers looked like a caterpillar when he saw the image upside-down through his camera lens. Holt liked it, and the name stuck. The history of the word “bulldozer” goes back to the 19th century when a bulldozer denoted a horizontal forging press used for shaping and bending metal. Another term, a bull-dose, was a large dose — literally effective for a bull — of any sort of medicine or punishment. Bull-dosing also meant coercion or intimidation. In the late 19th century, bulldozing meant using brute force to push over or through any obstacle, referring to two bulls butting heads in a fight. Today’s term might be a “bully.” During World War 1, Holt crawler tractors were used extensively by both American and British forces as ‘beasts of burden’ hauling heavy artillery and other heavy loads around the front lines where no other vehicles could handle the muddy conditions, Plant noted. It was also during World War 1 that the first tracked armored tanks were developed and were first used in combat by the British Army in September, 1916. In the late 1930s, the tracked vehicles became more common, and they became the go-to machine in the construction industry working on large projects like the building of Hoover Dam and the Golden Gate Bridge. By the 1940s, the term bulldozer referred to the entire machine and not just the attachment. Fleets of bulldozers were used in WWII to construct highways, runways and fortifications. Military bulldozers rumbled through bombed-out villages across Europe, working to clear roads and keep supply lines open, and rolled into camps as they were liberated by Allied forces. They were the first to go ashore on amphibious assaults, including the Normandy landings in 1944. Navy Admiral William Halsey said there were four things that helped win the war in the Pacific – airplanes, tanks, submarines and bulldozers.Following the war, the bulldozer cleared the rubble of bombed cities, built roads and leveled farmland in Europe. When President Eisenhower enacted the 1956 Federal Aid Highway Act, it meant the construction of the U.S. interstate system, and the bulldozer was center stage. The 1950s was an era of rapid growth and construction in the United States, but those years were equally significant for large-scale destruction in the name of progress, according to Francesca Russello Ammon, in her 2016 book, Bulldozer. In order to clear space for new suburban tract housing, an ambitious system of interstate highways, and extensive urban renewal development, wrecking companies demolished buildings while earthmoving contractors leveled land at an unprecedented pace and scale, she writes.Over the years, the bulldozer became an American icon. The size and sophistication of the machines grew, with the addition of automatic transmissions, hydraulic cylinders, electric motors, GPS technology and automatic grade control.“Many advances have been made over the years in bulldozer blade design and types, in crawler tractor design and in the design of controls for bulldozers. Horsepower has increased by well over 50 times and weights have likewise increased exponentially,” Plant said. “One can only wonder what Cummings and McLeod would think of today’s machines,” he said. What started out as a solution for farmers eventually became a solution for the construction industry. Today, this American icon is just a plain ‘ole “dozer.”